The present disclosure relates to an attachment mechanism of an optical scanner in an image forming apparatus, such as a copying machine, a printer or a multifunction machine, and the image forming apparatus.
An image forming apparatus typified by a copying machine, a printer or a multifunction machine is provided with a unit structure. In the unit structure, to a frame as a supporting structure arranged inside the image forming apparatus, a laser scanning unit (LSU) as an optical scanner is positioned and fixed.
As positioning and fixing parts of the LSU to the frame, for example, as shown in FIG. 9, it is well-known that an image forming apparatus is configured to fix LSUs 40 arranged for respective colors of four types of toners (developers) to a rectangular-liked frame 42 by fixing members 41. In detail, as shown in FIG. 10, on one side face of each LSU 40 in a longitudinal direction, a pair of positioning bosses 43 with round-shaped sections are formed. In the frame 42, openings 44 (refer to FIG. 11) capable of insertion of the positioning bosses 43 are formed. Moreover, the fixing member 41 is formed in a horizontally long rectangular plate-liked shape and, in an upper part of the fixing member 41, a pair of annular parts 45a and 45b are formed side by side.
In a lower part of one annular part 45a, as shown in FIG. 11, a back extending part 46 extending backward is formed and an outer circumference face of the back extending part 46 is configured to be capable of fitting to an internal circumference face of the opening 44. In addition, on internal circumference faces of both annular parts 45a and 45b, a plurality of ribs 47 projected slightly inward are formed and the ribs 47 are configured to be capable of fitting to outer circumference faces of the positioning bosses 43. On a back face of the fixing member 41, a projection 48 is provided outside and adjacent to the other annular part 45b and configured to capable of fixing a penetrating hole 49 correspondingly bored adjacent to the opening 44 of the frame 42.
Under such a configuration, in a situation of holding the positioning bosses 43 of the LSUs 40 by the openings 44 of the frame 42, the projection 48 is inserted in the penetrating hole 49 and the annular parts 45a and 45b are inserted between the positioning bosses 43 and the openings 44. Then, the outer circumference face of the back extending part 46 is fitted to the internal circumference face of the opening 44 and the ribs 47 are fitted to the outer circumference faces of the positioning bosses 43. Thus, after the positioning bosses 43 and annular parts 45 are positioned, the LSUs 40 are fixed to the frame 42 by screws 50 and a header pin 51 (refer to FIG. 10).
However, in the above-mentioned positioning and fixing parts, as shown in FIG. 12, transverse sections of respective opposite faces of the rib 47 and positioning boss 43 are formed in a straight line-liked shape. Therefore, when accuracy of these dimensions becomes uneven, a groove between these is caused to increase backlash in the attachment. Thereby, it is fear that accuracy of positioning the LSU is decreased and that, under the influence of oscillation, an image error is caused.
In addition, as other positioning and fixing parts for the LSU, another image forming apparatus is configured, when the LSU is located on an active position, to put a pair of left and right positioning axes in contact with positioning grooves of left and right side plates and to put a supporting projection in contact with a rear sideplate. Subsequently, in a situation of putting the LSU in non-contact with a rotating axis, the LSU is supported to an apparatus main body. In a further image forming apparatus, the LSUs are located side by side between a front side plate and the rear side plate and partitioned by a stay fixed between the front side plate and rear side plate. Moreover, an attachment member is attached between the side plates and the stay is also fixed to the attachment member. Subsequently, the attachment member is rotated in a situation of being applied to a stopper, thereby bringing the positioning of the attachment member.
However, in these techniques, it is fear that accuracy of dimensions of components becomes uneven to decrease accuracy of positioning the LSU.
Moreover, in a furthermore image forming apparatus, after a position adjusting part adjusts a positioning gap of an LSU attached to a block, the block with the positioning adjusted LSU is installed to a frame.
However, this technique requires labor and equipment for the positioning in separate process from the attachment.